In the 2008 Iron Man movie, a fictional miniature fusion energy device powers Tony Stark’s metal suit and protects his heart. A much larger version of the Arc Reactor powers the headquarters of Stark Industries.Fiction could soon become reality.The energy answer the world is increasingly betting on isn’t more oil, more gas or even more solar panels. It’s fusion, which could prove a vital source in the decades ahead.For a sector that was always 30 years away from success, suddenly it’s looking like it could be 10. Across the globe, dozens of start-ups and government-funded projects are working on ways…